1. Field of the Invention
The present invention relates to a method of bump formation, a semiconductor device and method of manufacturing the semiconductor device, a circuit board and an electronic instrument.
2. Description of Related Art
When forming bumps on the pads of a semiconductor chip, the method of forming bumps using electroless plating is known. For example, the method is known in which a resist layer is formed on the surface of a semiconductor chip so as to provide a plurality of penetrating holes, and with these penetrating holes as walls, bumps of straight form are formed.
However, in electroless plating, an alkaline solvent may be used, and because of this the patterned resist layer may be dissolved. If the resist layer is dissolved, penetrating holes corresponding to the narrow pitch of the pads cannot be formed, and it is not possible to form the bumps with a narrow pitch. With a rubber-based resist which resists solution in an alkaline solvent, after exposure to light, in the steps of resist layer development and removal, it is necessary to use an organic solvent, which presents handling problems, and makes the process difficult.